RichardS said:Hi Tom,
Thanks for your input, but I disagree. Adjusting the height of a MVB changes the amount of UV light reaching the substrate. The florescent tubes are at a constant distance from the animal and they run the length of the enclosure. Unlike ceramic heating elements, MVBs can't be hooked up to a thermostat to regulate the substrate temperature. I think the danger of overheating or dehydrating a hatchling tortoise of any species using an MVB is far greater than any perceived lack of UVB reaching the animal.
I keep my tubes about 11" off the substrate and change them out after 6 months. I really think you should try this with your next batch of hatchlings. Whomever pays your electric bills will thank you.
This is all fine and good, but you didn't address or acknowledge that they don't work. Do you have personal experience with dozens or hundreds of individuals of the species I mentioned being kept long term under those flourescent bulbs? I do. As I said, I've had to rehab dozens of them. If they come to me in the winter, during a cold spell, and I can't get them in the sun, I rehab them and stop the MBD using a MVB. I adjust the height of every one of them to get the desired temp. They make enough UV to stop MBD at any height. The flourescent tubes usually do not. I have had to rehab many reptiles from people who used flourescents. I have never seen MBD in any animal of any species kept under a MVB at any height.